1. Field of Invention
The present invention relates to blood analyzing systems of the kind that detect and analyze the composition of whole blood samples. More particularly, it relates to an improved blood analyzing system that is capable of automatically storing and transporting blood specimens and, upon pre-programmed and/or operator-determined command, of providing a blood smear on a microscope slide, e.g. for further study, verification and/or analysis.
2. Discussion of Prior Art
Currently, medical diagnosis is assisted greatly by systems which analyze whole blood samples to determine their detail compositional make-up. For example, the COULTER.RTM. STKS Blood Analyzer utilizes a unique hematology system in which three independent energy probes (viz. direct current, radio frequency and a stable helium-neon laser) cooperate to measure a blood cell's volume, conductivity and light scatter. Memory and control systems of the analyzer store and process detected cell information to provide the user with data (e.g, screen displays or print-outs) indicating the relative proportions of different cell types/populations constituting respective blood samples. Thus, in its various modes the analyzer can provide a wide variety of blood information, including hemograms, five part differential white blood cell counts and reticulocyte enumeration and analysis. While such information is useful in itself to diagnosticians, it sometimes occurs that a blood smear slide would be useful for further microscopically analyzing the sample and/or verifying the results of the analyzer system.
To produce a blood smear slide, it is necessary to withdraw an additional portion of blood from the sample container (e.g., a specimen vial), dispense a drop from that portion on a microscope slide and spread the drop on the slide to form a blood smear. U.S. Pat. No. 5,209,903, describes a system for automating these steps. It includes a conveyor assembly for moving racks of blood vials, first past one or more separate blood analyzers, and then past an automated slide-making apparatus. Each of these separate apparatus includes its own blood aspiration assembly, as well as the necessary supply, disposal and cleaning devices and fluids that are required to handle successive blood specimens in a clinical manner. In addition, each separate apparatus comprises its own bar code reading system to identify the individual vials, and its own vial handling mechanisms to present vials from the conveyor to its bar code reader and aspirator. In different site installations, the analyzer and slidemaker apparatus will often be arranged in different configurations, so the conveyor system for transporting vial racks are frequently custom designed or individually modified for each installation, which can present significant costs.
In addition to the structural and operational complexities presented by the '903 patent system, problems can be presented because the blood aspirations for the slidemaker and the different analyzer apparatus occur at different sample regions and at different times. Thus, because the vials containing the samples are moved to the different apparatus and repeatedly pierced with different probes of different aspirator devices, the blood specimen portions may be withdrawn from the different regions of the vials and the blood specimens from those different regions may have different characteristics. Similarly, because of the required vial transport periods between the analyzers and slidemakers, the specimens withdrawn can have temporal distinctions. Moreover, in the '903 system it is necessary for the blood smear testing of each vial in a given rack to await the completion of analyzer work on all other vials in the rack, which reduces significantly the system's flexibility regarding individual samples.
To obviate the many disadvantages of the approach that conveys sample containers between analyzers and the slidemaker, we have discovered a new approach for providing automated slide-making capabilities for blood analyzers, an approach that employs the clinically effective transport of blood specimens, via tubing, from a single aspiration site to both the analyzer apparatus and the slide-maker apparatus. Moreover, we have found that while blood is transported safely by plastic tubing for short distances, problems of sample integrity (such as cell morphology distortion, sample dilution and platelet losses) can occur when whole blood samples are transported over extended paths, e.g. between an analyzer apparatus and automatic slide-making apparatus. Also, we have found when blood samples are retained in a relatively immobile status for any substantial time, the cells begin to settle in a manner that can affect the homogeneity of the sample. If such changes occur to significant extents, a blood smear slide that is formed from such transported blood is not properly representative of the blood analyzed by the automated analyzer system, and no useful results will be achieved by microscope examination.